A number of eavestrough sections are known which utilize extruded plastic eavestrough sections joined by plastic moulded fittings. These systems can generally be divided into two types, one type utilizes a gasket arrangement for sealing with the length of eavestrough and the second type uses a solvent seal for securing of the eavestrough section within the fitting. Examples of the gasket type system are shown in our corresponding U.S. Pat. 4,901,954 and U.S. Pat. 4,257,716.
With plastic eavestroughing systems, the plastic has a relative high coefficient of thermal expansion and thus the fitting must accommodate a substantial movement of the eavestrough section within the fitting. Any gasket system accommodates this thermal expansion by allowing the eavestrough section to slide therewithin. These gasket type systems generally have a raised rib or deforming member which engages the lower surface of the eavestrough and provides a seal therewith.
In our earlier patents, a number of ribs are shown which contact the lower surface of the eavestrough section and provide a series of wiper seals along the bottom thereof. With systems of this type, the wiper member is the one which projects highest from the actual base of the eavestrough fitting and, therefore, there is a gap beneath the eavestrough section interior to the ribs in which water and other debris may accumulate, reducing the effectiveness of the seal.